Module
ActiveRecord::Relation::RecordFetchWarning

When this module is prepended to ActiveRecord::Relation and
config.active_record.warn_on_records_fetched_greater_than is
set to an integer, if the number of records a query returns is greater than
the value of warn_on_records_fetched_greater_than, a warning
is logged. This allows for the detection of queries that return a large
number of records, which could cause memory bloat.